<!DOCTYPE html>
<html lang="en">
	<head>
		<meta charset="UTF-8">
		<title>Document</title>
		<style>
			* {
				padding: 0;
				margin: 0;
			}

			.box {
				width: 300px;
				margin: 50px auto 0;
				background: red;
				/*zoom: 1;*/
				position: absolute;
				float: left;

			}

			/*.box::after {
				content: "";
				display: block;
				clear: both;
			}*/

			.a {
				width: 100px;
				height: 100px;
				background: blue;
				float: right;
			}

			.content {
				width: 500px;
				height: 500px;
				background: yellow;
				margin: 0 auto;
			}

			a {
				width: 100px;
				height: 100px;
				background: gold;
				float: left;
			}


		</style>
	</head>
	<body>

		<div class="box">
			<div class="a"></div>
		</div>

		<a href="">百度一下</a>

		<div class="content"></div>
		
	</body>
</html>